1. Field of the Invention
The present invention relates to a position detecting apparatus, an electronic part carrying apparatus including the position detecting apparatus, an electron beam exposure apparatus including the position detecting apparatus, and a position detection method. More particularly, the present invention relates to a position detecting apparatus, an electronic part carrying apparatus including the position detecting apparatus, an electron beam exposure apparatus including the position detecting apparatus, and a position detection method for minimizing influence of variation of a brightness distribution and deformation of a mark on an input image, and detecting a position of the mark accurately from the input image.
2. Description of the Related Art
In the manufacturing process of a large-scale integrated circuit (LSI), it is necessary to repeat a step of writing fine circuit patterns to wafer substrates, such as a semiconductor, and a step of depositing films. In order to make the LSI function as designed, the wafer substrate has to be positioned correctly in each step. Therefore, a mark is provided in advance on the wafer substrate and the wafer substrate is aligned by detecting the position of the mark. Conventionally, pattern matching processing, which compares a brightness distribution of a template image with that of the input image obtained by imaging the wafer substrate, and detects the position of the mark on the input image, is performed.
However, when depositing the films on the wafer substrate, the brightness may change locally near the mark, and deformation of the shape of the mark may be observed. Moreover, since the edge of the mark is damaged when performing chemical mechanical polishing (CMP) on the wafer substrate, the deformation of the shape of the mark is observed also in this case. Furthermore, when thickness of the lower films on the wafer substrate becomes uneven by the CMP, intensity of the reflected light may change with the differences in the layer thickness locally when a film is further deposited on the uneven films. In such a case, in the conventional pattern matching processing using the brightness, there has been a problem that the wafer substrate is not aligned correctly.